@gdivis, it would seem the image still have not been updated.
Using the "Linux and Docker Installation Guide" there are still issues when using the latest proget image.
After creating the proget-sql container as instructed, when executing the following command

docker run -d -v proget-packages:/var/proget/packages -p 4300:80 --net=proget --name=proget -h proget --restart=unless-stopped -e SQL_CONNECTION_STRING="Data Source=proget-sql; Initial Catalog=ProGet; User ID=sa;Password=<Secret>" inedo/proget

The following error is returned in the log and the container continuously retarts.

ProGet version is 5.2.32.5.
Attempting to use shared configuration for ProGet.
Shared configuration file loaded from /usr/share/Inedo/SharedConfig/ProGet.config.
No encryption key is configured. Credentials will be stored in plain text.
Current DB schema version is unknown.
Cannot open assembly '/usr/local/proget/db/bmdbupdate.exe': No such file or directory.

Inspecting the container (in Docker Desktop) shows the following variables.

Environment
SQL_CONNECTION_STRING = Data Source=proget-sql; Initial Catalog=ProGet; User ID=sa;Password=<Secret>

PATH = /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

MONO_VERSION = 6.10.0.104

PROGET_DATABASE = Server=proget-postgres; Database=postgres; User Id=postgres; Password=;

PROGET_DB_TYPE = PostgreSQL

PROGET_SVC_MODE = both

Mounts
/VAR/PROGET/PACKAGES = /var/lib/docker/volumes/proget-packages/_data

/USR/SHARE/INEDO/SHAREDCONFIG = /var/lib/docker/volumes/d46317bc74e4334d6ee4a6854b46b66220b3ac1217c2734163be4e6fcb8f6ba6/_data

/VAR/PROGET/EXTENSIONS = /var/lib/docker/volumes/b53c4441ac36102ba5121441916e5889b0f456ad14906795b13d7c03dc877741/_data

Port
80/tcp = localhost:4300